How to use this plugin:

1. install it into Joomla (2.5 or 3.x).  Open the plugin, declare which components are check for overriding XML files, declare the platform, enable, and save. 

• Copy the XML forms file to the new folder.  You will always find this file under the component's /models/forms directory (for both the site and administrator directories.  The overriding files should be copied to the respective directory:
  for administrator:  
        /administrator/templates/system/forms/
  for site: 
        /templates/system/forms/
  So to override com_contact's form in the admin section: /administrator/templates/system/forms/com_contact/contact.xml

• Edit the copied file to implement the changes you want:  Change field attributes or add fields.

If  you are adding fields to a component, you will need to add that field in the component's database and you will need to add that field within each layout file that creates or edits records for this database. 

As a result of your changes to the XML file, the screens that display these fields will reflect the changes (size, required, filters, etc.)

This plugin works on a any component that uses JForm with the XML field declarations.  All core components within Joomla use the XML files for their fields.  Some third-party components do not, and in those cases this plugin will have no effect.  We recommend you choose components that leverage Joomla's JForms and XML field declarations.